I cancelled my snipe when the auction still alive, but when the auction ended, I won! I am very surprised.

And I went back to myibidder.com saw my bid is "NO" instead of the price of the item I won.

Anyone give me a explain on this. I have to either pay for it or lose my credit on ebay.

You cancelled it too late (just a few seconds before auction ended, when snipe was executed already).
Please check the following FAQ section for more information:
http://www.myibidder.com/login/faq/4/#q6

Thanks! But now i got face the seller with shit on my face.

I'm sorry, it has nothing to do with the sniper.
The seller can make a second chance offer to the next bidder.